The present invention relates generally to the ink jet printing art, and in particular, to a hand-held marking device which utilizes an ink jet print-head in order to selectively apply ink to a print medium. Preferably, the print-head is part of a replaceable cartridge that may be replaced as desired.
Various ink jet technologies that are utilized in conjunction with printer devices are known in the art. These generally include continuous feed ink jet systems and drop-on-demand systems. One such printer that is based on a drop-on-demand system utilizes a print-head that is disposed on a carriage. The carriage is translatable over a print medium. Relatively sophisticated electronics are employed including timing and encoding circuitry to move the print medium in a first direction and to move the carriage in an orthogonal direction thereto.
The print-head in these systems typically comprises a piezoelectric transducer, an ink chamber, and an ejection nozzle. The transducer is disposed to selectively vibrate the ink chamber in proximate relation to the ejection nozzle. In operation, a non-pressurized ink pulse jet is generated at a desired frequency, i.e., 1 to 10 kHz. The ink drops are generated on demand by a transient pressure pulse and directed toward a receiving surface. Volume changes in the ink chamber located behind the ink ejection nozzle cause the droplets to eject. These volume changes are generated by the piezoelectric transducer.
The impulse jets are relatively compact in design. Accordingly, print-heads based on this technology typically have arrays which include tens of nozzles operating synchronously.
Another technology which is known is the xe2x80x9cbubble jetxe2x80x9d or thermal jet printing technology. In these types of printers, a supply channel is provided which leads from an ink reservoir to one or a plurality of nozzles on an orifice plate. This supply channel is designed to provide a certain amount of resistance to flow. A thermo-electric transducer disposed proximate to the supply channel heats up the ink and produces a small vapor bubble. The vapor bubble drives the ink from the nozzle with a certain force. The maximum ejection frequency is approximately 4 kHz.
While these systems perform satisfactorily in printing capacities for which they are intended, it would be desirable to have a hand-held marking device based on these technologies.
Accordingly, it is an object of the invention to provide a hand-held marker that utilizes an ink jet technology.
It is a further object of the invention to provide an ink jet marker which is relatively simple in design and construction.
It is a further object of the invention to provide an ink jet marker which includes a replaceable cartridge that may be readily installed or removed from a marker body.
The present invention provides these and other additional objects and advantages in an ink jet marking device. The marking device comprises an elongated body of a generally cylindrical or other desired shape that is adapted for use as a writing instrument. A cartridge containing a reservoir of ink is disposed within the body. Preferably, the cartridge also comprises an ink jet print-head disposed at one end of the instrument body in fluid communication with the reservoir. The print-head includes at least one ejection nozzle adapted to dispense a selected amount of ink upon receipt of first control signals by the print-head. The marking device also comprises an electrical circuit coupled to the ink jet print-head disposed to provide the first control signals to the ink jet print-head.
In one embodiment, the electrical circuit is located in a base station console. The electrical circuit is connected to the print-head with electrical terminals. Alternatively, the electrical circuit is disposed within the cylindrical body of the marking device.
In another aspect of the invention, a replaceable ink cartridge is provided for insertion within a hand-held writing instrument body. The cartridge includes a print head and an enclosure containing a reservoir of ink adapted for placement within the body. At one end of the enclosure is an ink jet writing or print-head. The print-head includes a transducer, and an ejection nozzle coupled with the reservoir. The transducer is adapted to provide a disturbance that dispenses a selected amount of ink upon receipt of control signals provided by an electrical circuit. In one embodiment, a thin film battery is wrapped around the reservoir body.